JPH05220997A - Thermal head and production thereof - Google Patents

Abstract

PURPOSE:To provide a thermal head miniaturized in its constitution and enhanced in reliability related to electrical connection. CONSTITUTION:A heat-resistant substrate 34 and an external wiring board 40 are arranged on a radiation plate 35 in an adjacent state and flatness adjusting pieces 50,50a and a driving circuit element 37 are alternately fixed on the boundary of them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head used as a so-called line printer or serial printer and a method for manufacturing the same.

[0002]

2. Description of the Related Art FIG. 11 shows a first conventional thermal head 1
12 is a perspective view of FIG. 12, and FIG. 12 is a cross section line X12-X of FIG.
It is sectional drawing seen from 12. The thermal head 1 includes a heat resistant substrate 2 made of an electrically insulating material such as alumina, and a common electrode 3b, a plurality of individual electrodes 3c, and a heating resistor array 3a defined by these electrodes are formed on the main surface thereof. To be done. The individual electrodes 3c are respectively connected to a plurality of drive circuit elements 4 in a predetermined number, and each drive circuit element 4 is covered with a protective resin layer 24. A ground electrode 25 is formed on the insulating substrate 2 for each drive circuit element 4.

A flexible film-shaped external wiring substrate 7 for supplying display data for driving and various control signals to the insulating substrate 2 and the drive circuit element 4 is fixed to the heat sink 5 via an adhesive 15. To be done. The external wiring board 7 has a bonding portion 26 near the end of the insulating substrate 2 opposite to the heating resistor array 3a.
Is connected to the common electrode 3b on the insulating substrate 2, the ground terminal 25, and the plurality of signal lines for supplying display data and various control signals for the printing operation to the drive circuit element 4. A connector 10 for connecting to an external electric circuit is further attached to the external wiring board 7 by a connection terminal 14. The drive circuit element 4 has solder bumps 27 and is connected to the individual electrodes 3c, the ground electrode 25 and the like by face down bonding. Such a conventional thermal head 1 has the following problems.

(1) The length (hereinafter, referred to as width) W1 of the insulating substrate 2 in the sub-scanning direction and the width W2 of the external wiring substrate 7 shown in FIG.
It is difficult to downsize. That is, if the length L1 of the heating resistor array 3a and the drive circuit element 4 is excessively reduced, the protective resin layer 24 comes into contact with the platen roller 13, so there is a limit to the reduction. Further, since the individual electrode 3c and the ground electrode 25 on the insulating substrate 2 are formed by depositing aluminum in a film thickness of 1 μm, for example, the conductor resistance loss is relatively large. Therefore, the joint portion 26 of the external wiring substrate 7
Must be arranged as close to the drive circuit element 4 as possible. This is because it is easy to form the circuit wiring of the external wiring board 7 to have a film thickness of 10 μm or more, and the conductor resistor loss is small. However, the drive circuit element 4 needs to be covered and protected with the protective resin 24 to prevent damage. Furthermore, a connection region L2 (28) is required at the connection portion between the insulating substrate 2 and the external wiring substrate 7.

(2) As described above, the circuit wiring on the insulating substrate 2 maintains good contact between the surface of the protective layer covering the heating resistor array 3a on the insulating substrate 2 and the thermal paper 12. As described above, the film is formed to have a film thickness of about 1 μm, for example. As a result, there is a problem that the conductor resistance loss is large in the common electrode 3b, the individual electrode 3c, the ground electrode 25, etc., and uneven density occurs during heat-sensitive printing, or the printing efficiency is poor.

FIG. 13 is a sectional view of a typical second conventional thermal head 1a. The thermal head 1a is provided with a heat resistant substrate 2 having electrical insulation properties, and a heating resistor array 3 is formed on the thermal head substrate 1a so as to extend in a direction perpendicular to the plane of FIG.
A drive circuit element 4 for selectively driving the heating resistor array 3 to generate heat is mounted on the heat-resistant substrate 2, and the heat-resistant substrate 2 is bonded to a radiator plate 5 made of, for example, aluminum.

The drive circuit element 4 is mounted on the heat sink 5 via a spacer 6, and a connector 10 for connecting to an external electric circuit is further connected to an external wiring board 7 to which a connecting terminal 14 is attached. To be done. The area of the external wiring board 7 on the heat sink 5 and the external wiring board 7 and the heat resistant board 2
A head cover 8 is provided to cover a range extending over the connection portion with. The head cover 8 is screwed to the heat sink 5 via the external wiring board 7 and the spacer 6 with a screw 9.

The head cover 8 is a platen roller 1
It has a function of smoothly guiding the heat-sensitive paper 12 in a predetermined direction when the heat-sensitive paper 12 pressed by 3 slides on the heating resistor array 3, and is an essential component of the thermal head 1. ..

In the second conventional example as described above, the head cover 8 is fixed to the heat dissipation plate 5 with the screws 9, so that it is necessary to provide the external wiring board 7 with a plurality of insertion holes 11 through which the screws 9 are inserted. .. For this reason, the circuit wiring formed on the external wiring board 7 is laid out avoiding the plurality of insertion holes 11, which complicates the circuit wiring. Further, it is necessary to make the size of the heat-resistant substrate 2 larger than the size determined only by the specifications of the necessary circuit wiring.
However, there is a problem that it hinders the downsizing and the downsizing of the external wiring board 7. Further, there is a problem that the circuit wiring around the insertion hole 11 is likely to be broken due to the work of attaching the screw 9 to the insertion hole 11.

FIG. 14 is a sectional view of a thermal head 1b of a third conventional example. This conventional example is similar to the thermal head 1a shown in FIG. 13, and is characterized in that the head cover 8 is provided with the terminal covering portion 15 of the connection terminal 14 of the connector 10 protruding from the external wiring board 7. Also in this conventional example, the head cover 8 is attached to the heat radiating plate 5 by the screw 9 and has the same problem.

In the fourth conventional thermal head 1c shown in FIG. 15, a head cover 8 having the same function as the head cover 8 in the thermal head 1b is formed by bending a plate-like body. Since the head cover 8 made of this plate-like member is attached to the heat dissipation plate 5 with the screw 9, it has the same problems as described above.

The thermal head 1d shown in FIG. 16 has a separate wiring board 16 on the heat sink 5 which is different from the heat resistant board 2.
Is mounted, and the drive circuit element 4 is mounted thereon. In this conventional example, another wiring board 17 is provided on the heat sink 5, and the heat resistant board 2, the drive circuit element 4, and the wiring board 17 are provided.
Are connected by a film carrier tape 18 on which flexible film-like circuit wiring for connection is formed. The head cover 8 of this conventional example is the same as the wiring board 1 described above.
7, the film carrier tape 18, and a range including a part of the heat resistant substrate 2 are covered, and the pillars 19 are provided. The head cover 8 is also screwed to the heat sink 5 at a portion not shown. Such a thermal head 1d also has the same problems as described above.

In the thermal head 1e shown in FIG. 17, the drive circuit element 4 is mounted on a separate wiring board 17 different from the heat resistant board 2, and the heat resistant board 2 and the wiring board 17 are bonded onto the heat dissipation plate 5. The common electrode 20 for the heating resistor array 3 is connected to the wiring board 17 by a lead wire 21.
The head cover 8 of this conventional example is formed by bending a plate-shaped body,
It is fixed to the heat sink 5 with the screw 9 via the wiring board 17. Therefore, this conventional example also has the same problems as those described above.

FIG. 18 is a sectional view of still another conventional thermal head 1f. In this conventional example, the drive circuit element 4 is mounted on the wiring board 17 different from the heat resistant board 2,
Cover piece 2 for covering the drive circuit element 4 from the wiring board 17
2 and a head cover 8 integrally provided with a locking piece 23 that penetrates the wiring board 17 and projects below the heat dissipation plate 5. Therefore, the head cover 8 is fixed to the heat dissipation plate 5 by the locking piece 23. That is, even in this conventional example, although the screw 9 in the conventional example is not used, the working process can be simplified to some extent, but it still has the same problems as those described in the conventional example. ..

In order to solve such a problem, there is a technique of mounting the drive circuit element 4 in a state of straddling the insulating substrate 2 on which the heating resistor is formed and the external wiring substrate 7, as disclosed in JP-A-59-59.
No. 2865. However, in this conventional example, it is difficult to mount and electrically connect the drive circuit element 4 due to the variation in the thickness of each substrate. In addition, drive circuit element 4
Since the width of the ground electrode 25 along the sub-scanning direction is as small as about 1 mm, for example, it is difficult to increase the width of the ground electrode 25 along the main scanning direction. Has the problem of causing various problems.

[0016]

All of the above-mentioned conventional examples have a problem that the structure is large and the reliability regarding electrical connection is low.

It is an object of the present invention to provide a thermal head and a manufacturing method thereof which can solve the above-mentioned technical problems, reduce the size of the structure, and improve the reliability of electrical connection. Is.

[0018]

According to the present invention, a heat-resistant substrate having a plurality of heat-generating resistors and electrodes for energizing the heat-generating resistors is formed on a first main surface, and a heat-resistant substrate is a second main substrate. In a thermal head including a heat dissipation member that is adhesively fixed on a surface and an external wiring board that is disposed adjacent to the heat resistant board on the heat dissipation member, the thermal head extends between the adjacent end portions of the heat resistant board and the external wiring board. Then, the integrated circuit element for energizing and driving the heating resistor and the flatness adjusting piece are fixed to each other.

Further, according to the present invention, a heat-resistant substrate having a plurality of heating resistors and electrodes formed on the first main surface is adjacent to an external wiring substrate and mounted on an elastic mounting member, Next, the flatness adjusting piece and the integrated circuit element for energizing and driving the heat generating resistor are fixed to each other between the end portions of the heat resistant substrate and the external wiring substrate, and then the heat resistant substrate and the external wiring substrate are pressed by the pressing member. Manufacturing of a thermal head characterized in that the first main surface is adjusted to be flush with each other by pressing in common, and then the insulating substrate and the external wiring substrate are adhesively fixed on the heat dissipation member. Is the way.

[0020]

According to the present invention, the heat-resistant substrate having the plurality of heat generating resistors and the electrodes formed on the first main surface and the external wiring substrate are adjacent to each other and mounted on the elastic mounting member. Then, the flatness adjusting piece and the integrated circuit element for energizing and driving the heating resistor are fixed to each other between the adjacent end portions. After that, the heat resistant substrate and the external wiring substrate are commonly pressed by the pressing member to adjust the first main surfaces of these to be flush with each other. Then, the heat resistant substrate and the external wiring substrate are adhesively fixed on the heat dissipation member.

This eliminates the need to overlap the heat resistant substrate and the external wiring substrate in the vicinity of the ends where they are connected to each other, and the widths of the insulating substrate and the external wiring substrate can be suppressed respectively, and the thermal head The configuration can be downsized. Further, the integrated circuit element is fixed in a state of straddling the insulating substrate and the external wiring substrate, but the flatness adjusting pieces of the respective substrates keep the first main surfaces flush with each other. As a result, the reliability of connection of the integrated circuit element to each substrate is significantly improved. In addition, it is possible to reduce the range of the conductor used for input or output of the integrated circuit element, which is formed on the insulating substrate, and thus it is possible to suppress the conductor resistance loss and to cause density unevenness during heat-sensitive printing and lower printing efficiency. Can be prevented.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a thermal head 3 according to an embodiment of the present invention.
1 is an enlarged perspective view of FIG. 1, FIG. 2 is a perspective view of the thermal head 31, FIG. 3 is a sectional view taken along the section line X3-X3 of FIG. 2, and FIG. 4 is a heating resistor array of FIG. FIG. 33 is an enlarged sectional view around 33.

The thermal head 31 includes a heating resistor array 33.
Formed linearly, for example, aluminum oxide Al ₂
A heat resistant substrate 34 made of ceramic such as O ₃ is provided. The heat resistant substrate 34 is adhered via an adhesive layer 36 onto a heat dissipation plate 35 obtained by press molding or die casting of aluminum or the like.

A heat storage layer 41 made of, for example, glass is formed on the heat-resistant substrate 34, and tantalum nitride T is formed on the heat storage layer 41.
A resistor layer 42 made of a ₃ N ₄ or the like is formed over the entire surface. On the resistor layer 42, a metal such as aluminum is patterned by a thin film technique to have a film thickness of about 1 μm, for example, and a common electrode 43 and a plurality of individual electrodes 44 are formed.
Are formed, and individual heating resistors 32 are formed. A protective layer 47 made of tantalum pentoxide Ta ₂ O ₅ , silicon nitride Si ₃ N ₄ or the like is formed so as to cover the heating resistor 33, the common electrode 43, and the individual electrode 44.

An upper surface of the heat dissipation plate 35 is formed flat, and a connector 49 made of ceramic is electrically connected to the drive circuit element 37 on the heat resistant substrate 34 via the adhesive layer 36. The external wiring board 40 is fixed adjacent to the heat resistant board 34.

On the boundary 48 between the heat resistant substrate 34 and the external wiring substrate 40, the heating resistor array 33 is driven to generate heat, and for example, solder bumps 59 made of a material having a relatively low melting point (less than 250 ° C.) are provided. The plurality of drive circuit elements 37 and the flatness adjusting pieces 50 are arranged alternately in parallel to the arrangement direction of the heating resistor row 33, and the drive circuit elements 37 and the flatness adjusting pieces 50 are arranged.
Is a protective layer 38 made of, for example, an epoxy resin.
Is covered with.

FIG. 5 is a sectional view taken along section line X5-X5 in FIG. 1, and FIG. 6 is a sectional view taken along section line X6-X6 in FIG. Please refer to these drawings together. As shown in FIGS. 1 and 2, a plurality of flatness adjusting pieces 50 are fixed between the plurality of drive circuit elements 37 on the boundary 48 and near both ends of the heating resistor row 33 in the arrangement direction. As shown in the cross-sectional view of FIG. 7, the flatness adjusting piece (hereinafter abbreviated as adjusting piece) 50 has a surface facing the heat resistant substrate 34 or the external wiring substrate 40 made of, for example, iron plated with copper. The metal plate 51 is made of a heat-resistant synthetic resin material, for example, a resin layer 52 such as a polyimide resin is formed on the opposite surface.

The installation area 53 of the drive circuit element 37 shown in FIG. 1 is provided over the heat resistant substrate 34 and the external wiring board 40. On the heat resistant substrate 34 side, the free end portion of the individual electrode 44 is the pad portion. Included as 54. On the other hand, the external wiring board 40 is used as a double-sided board and supplies a plurality of display data and various control signals for the printing operation to the drive circuit element 37 on one surface of the support body 55 made of an electrically insulating ceramic or the like. Signal line 56 is provided, and its free end portion is configured as a pad portion 57.

On the other hand, the heat resistant substrate 34 of the external wiring substrate 40.
A through hole 58 having a shape in which the end is cut out is formed near the side end, and the bump 59 of the drive circuit element 37 is formed.
The connection terminal 60 on the one surface side connected to the electrode conductor 61 is formed on the other surface of the support body 55 through the through hole 58 so as to be relatively wide and, for example, a thick film of several tens of μm or more. To be done. That is, when the connection terminal 60 is connected to the ground electrode of the drive circuit element 37, such conductor resistance loss of the ground line can be significantly suppressed. As a result, it is possible to eliminate density unevenness during printing operation and improve printing efficiency.

Flatness adjusting pieces 50a at both ends in the arrangement direction
A cross section of is shown in FIG. That is, as shown in FIG. 2, the common electrodes 43 routed along the outer periphery of the heat resistant substrate 34 are led out to the external wiring substrate 40 side near both ends in the longitudinal direction of the heat resistant substrate 34, and the external wiring substrate 40. The common electrode conductor 62 formed above is electrically connected via the flatness adjusting piece 50a. That is, the common electrode 43 and the common electrode conductor 62 are fixed via the metal plate 51 of the flatness adjusting piece 50a and the solder layer 63 having a relatively high melting point (for example, 250 ° C. or higher).

As described above, the flatness adjusting pieces 50 at the positions other than the both ends in the arrangement direction are provided on the heat resistant substrate 34 and the external wiring substrate 40, for example, the heat resistant adhesive 6 having a heat resistant temperature of 250 ° C.
It is fixed through 4. Positioning indicators 67 and 68 having notches 65 and 66 formed on the sides thereof are formed on the heat-resistant substrate 34 and the external wiring substrate 40 when patterning the individual electrodes 44 and the signal lines 56. A solder resist 69 is formed on this. On the resin layer 52 of the flatness adjusting piece 50, for example, a triangular positioning indicator 7 is provided at a position corresponding to the notches 65 and 66.
0 and 71 are formed by printing, for example.

FIG. 9 is a sectional view for explaining the manufacturing method of the thermal head 31 of this embodiment, and FIG. 10 is a process drawing for explaining this manufacturing method. In step a1, the suction hole 7
A support base 74 having the holes 2 and 73 is prepared, and an elastic sheet 77 having suction holes 75 and 76 communicating with the suction holes 72 and 73 is mounted thereon. The elastic sheet 77 is
For example, it is formed from a heat-resistant rubber material such as silicon rubber. The elastic sheet 77 is made of the heat resistant substrate 34.
Is deformed by the difference d1 between the plate thickness t1 of the external wiring board 40 and the plate thickness t2 of the external wiring board 40 to adjust the upper surfaces of the heat resistant board 34 and the external wiring board 40 to be flush with each other. The suction holes 72, 73; 75, 7
6 is connected to a vacuum source, and the heat resistant substrate 34 and the external wiring substrate 40 are temporarily fixed to the support base 74.

In step a2, the flatness adjusting piece 50 is mounted on the boundary 48 between the two. On the lower surface of the flatness adjusting piece 50,
Either the solder layer 63 or the heat resistant adhesive 64 as described above is provided corresponding to the grounded position. The flatness adjusting pieces 50 are arranged alternately with the driving circuit elements 37. In step a3, a pressing jig 79 for embedding a heater is brought into contact with the range including the flatness adjusting piece 50, and pressing is performed while heating. As a result, the flatness adjusting piece 50 is fixed to the heat resistant substrate 34 and the external wiring substrate 40. Process a
In 4, the heat-resistant substrate 34 and the external wiring substrate 40 are fixed to the heat dissipation plate 35 as shown in FIGS. 2 and 3 to assemble the thermal head 31.

As described above, according to the present embodiment, the overlap margin between the heat resistant substrate and the external wiring board in the conventional example can be eliminated, and the width of the heat resistant substrate 34 is 2 in comparison with the conventional example.
It can be reduced by 0 to 30%. In addition, the external wiring board 4
In the case of 0, the width can be reduced by 20 to 30%, the thermal head 31 can be downsized by combining them, and the cost can be reduced. Further, the conductor resistance loss related to the input / output of the drive circuit element 37 can be reduced to 1/10 or less, and it is possible to eliminate the density unevenness during the printing operation and improve the printing efficiency.

[0035]

As described above, according to the present invention, there is no need to overlap the insulating substrate and the external wiring substrate in the vicinity of the ends where they are connected to each other, and the width of the insulating substrate and the external wiring substrate is eliminated. Can be suppressed, and the thermal head can be downsized. Further, the integrated circuit element is fixed in a state of straddling the insulating substrate and the external wiring substrate, but the flatness adjusting pieces of the respective substrates keep the first main surfaces flush with each other.
As a result, the reliability of connection of the integrated circuit element to each substrate is significantly improved. In addition, it is possible to reduce the range of the conductor used for input or output of the integrated circuit element, which is formed on the insulating substrate, and thereby suppress the conductor resistance loss.
It is possible to prevent the occurrence of density unevenness and the reduction in printing efficiency during heat-sensitive printing.

[Brief description of drawings]

FIG. 1 is an enlarged perspective view of a thermal head 31 according to an embodiment of the present invention.

FIG. 2 is a perspective view of a thermal head 31.

3 is a cross-sectional view taken along the section line X3-X3 in FIG.

FIG. 4 is an enlarged sectional view of a thermal head 31.

5 is a cross-sectional view taken along the section line X5-X5 in FIG.

6 is a cross-sectional view taken along the section line X6-X6 in FIG.

FIG. 7 is a cross-sectional view of a flatness adjusting piece 50.

FIG. 8 is a cross-sectional view related to a flatness adjusting piece 50a.

FIG. 9 is a cross-sectional view illustrating the manufacturing process of the thermal head 31.

FIG. 10 is a process diagram illustrating a manufacturing process of the thermal head 31.

FIG. 11 is a perspective view of a conventional thermal head 1.

12 is a cross-sectional view taken along the section line X12-X12 in FIG.

FIG. 13 is a sectional view of a conventional thermal head 1a.

FIG. 14 is a sectional view of a conventional thermal head 1b.

FIG. 15 is a cross-sectional view of a conventional thermal head 1c.

FIG. 16 is a sectional view of a conventional thermal head 1d.

FIG. 17 is a cross-sectional view of a conventional thermal head 1e.

FIG. 18 is a cross-sectional view of a conventional thermal head 1f.

[Explanation of symbols]

 31 thermal head 33 low heat generation antibody column 34 heat resistant substrate 37 drive circuit element 40 external wiring substrate 50, 50a flatness adjusting piece 74 support base 77 elastic sheet 79 pressing jig

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location 8906-2C 113 B

Claims (2)

[Claims] 1. A heat-resistant substrate having a plurality of heating resistors formed on a first main surface and electrodes for energizing the heating resistors, and a heat-dissipating member to which the heat-resistant substrate is adhesively fixed on the second main surface. And a thermal head including an external wiring board disposed adjacent to the heat-resistant board on the heat dissipation member, the heating resistor is energized and driven between the adjacent ends of the heat-resistant board and the external wiring board. The thermal head is characterized in that the flatness adjusting piece and the integrated circuit element to be fixed are fixed. 2. A heat-resistant substrate having a plurality of heating resistors and electrodes formed on a first main surface and an external wiring substrate are placed adjacent to each other and mounted on an elastic mounting member, and then heat-resistant. By fixing the flatness adjusting piece and the integrated circuit element for energizing and driving the heating resistor across the ends of the board and the external wiring board,
After that, the heat resistant substrate and the external wiring substrate are commonly pressed by the pressing member to adjust the respective first main surfaces to be flush with each other, and then the insulating substrate and the external wiring substrate are adhered onto the heat dissipation member. A method of manufacturing a thermal head, characterized in that it is fixed.